Field of the Invention
The present invention relates to a technique for acquiring depth information of objects from a captured image.
Description of the Related Art
Conventionally, an image capturing apparatus is known that can acquire information corresponding to the depths of objects in a captured image (e.g., distance information). The distance information acquired from the image is updated as needed on the assumption that a desired object and the image capturing apparatus move, or updated when a movement is detected. Such an image capturing apparatus may be an onboard camera mounted on a vehicle, for example, an automobile, and used for the purpose of acquiring distance information indicating a distance to a desired object, such as a leading vehicle travelling in front of a self-vehicle, using a captured image of the leading vehicle.
An image capturing apparatus acquires distance information of objects as follows: a plurality of focus detection regions are set in a captured image for calculation of distance information, and for each focus detection region, distance information indicating a distance between a desired object present in the focus detection region and the image capturing apparatus is calculated. At this time, a limited number of focus detection regions can be set to reduce a calculation load; this enables acquisition of distance information of objects at higher speed (Japanese Patent Laid-Open No. 2006-322795).
However, according to Japanese Patent Laid-Open No. 2006-322795 mentioned above, in updating distance information acquired through selection of a part of focus detection regions that includes an object detected as a moving object, the order of priority of calculation is not particularly determined for the focus detection regions. Therefore, calculation of distance information may take time in a focus detection region including, for example, a rapidly approaching object (e.g., a person or a vehicle), even though such a focus detection region should be prioritized over other focus detection regions in calculation of distance information.